The Use of Electronic Leak Detection (ELD) on Waterproofing Membranes over Concrete Surfaces
Waterproofing membranes are a key element in building enclosure systems—a key element that ultimately gets covered up by a variety of finish materials including landscaping, green roofs, topping slabs, pavers and so on. As most of us know, excavation to expose a failed waterproofing membrane for repairs can be prohibitively expensive and in some cases impossible. For this reason, many designers are choosing to specify integrity testing to verify that the waterproofing membrane is free of discontinuities and penetrations through the membrane prior to the installation being permanently covered. When integrity testing is not specified, many contractors are often performing this type of testing voluntarily to avoid future problems or “call-backs.”
The most common integrity testing method is the flood test. Flood testing is typically performed by flooding waterproofed horizontal surfaces with at least two inches (50 mm) of water for a period of up to 48 hours. Temporary dams are often constructed to partition the test areas, provide an up-turned plaza edge and control the depth of the flood testing. During the flood test, access to the underside of the flooded areas is necessary for a visual inspection of water leakage. However, in the case of a membrane failure (leak), flood testing indicates only where water is penetrating through the entire assembly within the test area, not the location above where water is breaching the membrane. In addition, flood testing cannot be performed on vertical surfaces or at locations where the underside of the slab is not accessible.
The aforementioned restrictions and lack of conclusive data associated with flood testing has enabled Electronic Leak Detection (ELD) to gain momentum as a viable alternative to traditional flood testing. This article will focus on the different types of ELD and the applications where ELD is or is not well-suited.